My iMac 21.5" Mid-2011 (i5 2.7 GHz) has started exhibiting a strange behavior where small colored squares, about 1/8", appear all over the screen. They then proceed to dance around the screen as I continue to work on the computer. I've attached a screen shot. From searching the forums it appears others have this problem, but I am unable to find any threads that actually contain a fix. Any help would be very much appreciated!
Hello,
I have exactly the same problem with exact hardware. I have reinstalled OS X several times, but the problem persists and finally it gets frozen and a button restart is required. Any ideas?
David.
iMac 21.5 Mid 20112.8GHz i7 with AMD Radeon HD 6770M 512MB
Same issue. It's becoming unusable.
DAlvarez72 - Thank you for mentioning the freezing computer. Mine does that as well (fairly regularly). Yesterday I ran Apple Hardware Test (extended) two times. Both tests came back saying that no problems were found.
Could this possibly be a much bigger issue with Mid-2011 iMacs and El Capitan?
So this latest manifestation of the problem has me scratching my head... This capture was taken from my Win 7 Boot Camp (virtualized through Fusion 8.1). It appears the little squares are somehow behind the opaque Win 7 toolbar. I have no idea what conclusion to draw from this!
Same Problem here with iMac Mid 2011 Core i7 and El Capitan. Any fix?
Nothing yet...
Same here, I have lived with this for two and a half years now. A couple months ago I did a complete tear down of my 2011 iMac and used a high end thermal paste on all the heat sinks and had some success for about a month then it started to come back. Since then the only thing I have been able to do to limit but not eliminate the problem has been to reduce the resolution of the screen. I suspect strongly it is a video card failure. Is there no solution??
kindred5, have you run an Apple Hardware Test? I also suspected the video card, but ran the extended AHT multiple times and it always says all hardware is fine.
I tried the hardware test, I even tried running it multiple times in a row in an effort to get the problem to be detected. I am considering buying a new graphics card from here http://www.allpartsmac.com/ has anyone had any luck with this route?
I have also considered replacing the graphics card but decided to hold out because of the AHT saying everything is fine. I'm thinking of throwing in the towel and taking it in to the Apple Store today. It's almost unusable at this point. Freezes every few hours.
Out of curiosity, is anybody running dual monitors via the Thunderbolt port? I am, and am wondering if that is possibly stressing the relatively old graphics card?
Unfortunately, your graphics card is going bad and there is no software solution for it.
If you are still under warranty or have AppleCare, take it to the Apple Store and have them replace your graphics card and/or the logic board.
If your machine is out of warranty, no AppleCare...you can still take it back to Apple or an authorized service center but they may charge you through the nose for replacement.
The cheapest/safest route is having the graphics chip reballed by a qualified BGA reball tech. (if you don't know what this is, look up BGA Reball on YouTube)
The cheapest/less safe route would be to heat your GPU chip with a heat gun or by baking it in the oven. There are tons of videos on YouTube on how to do this and you can get a GPU to work again using the heat method BUT it will just buy you a few months (if you're lucky) because when the GPU starts artifacting, there is something structurally wrong with the chip itself. Worst case scenario is you completely destroy the chip and/or damage your machine. Mileage varies a lot on this technique so beware.
Just dropped my iMac off at the local Apple Store. They did a limited amount of testing (not as much testing available for older models) and were pretty confident the graphics card is the culprit (echoing Eddie Jasmine). They are going to replace the card and get it back to me in 2-3 days. Total will be $175 ($135 for the card and $40 for labor) assuming replacing the card fixes the problem. I'll keep you all posted.
Just picked up my iMac after the repair. So far no signs of the little squares and no freezing. I'll report back in a week or so.
Small squares all over screen
